Apparatus comprising expandable bistable tubulars and methods for their use in wellbores

ABSTRACT

A technique for connecting expandable tubulars. The technique comprises an expandable connector system that facilitates the connection of tubular components, such as tubulars used in wellbore environments.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. Ser. No. 10/035,994, filed Dec. 26, 2001now U.S. Pat. No. 6,648,071, which claims the benefit under 35 U.S.C.§119(e) to U.S. Provisional Application Ser. No. 60/263,934 filed Jan.24, 2001.

FIELD OF THE INVENTION

This invention relates to equipment that can be used in the drilling andcompletion of wellbores in an underground formation and in theproduction of fluids from such wells; and is particularly to connectionsystems for connecting a variety of tubulars used in wellbores.

BACKGROUND OF THE INVENTION

Fluids such as oil, natural gas and water are obtained from asubterranean geologic formation (a “reservoir”) by drilling a well thatpenetrates the fluid-bearing formation. Once the well has been drilledto a certain depth the borehole wall must be supported to preventcollapse. Conventional well drilling methods involve the installation ofa casing string and cementing between the casing and the borehole toprovide support for the borehole structure.

Within the casing or within the open wellbore, a variety of tubularcomponents are utilized in, for example, preparation and servicing ofthe well and for the production of wellbore fluids. In someapplications, the use of expandable tubulars is becoming more desirable.In such applications, a tubular component is moved downhole and thenexpanded at a desired location within the wellbore. With these types oftubulars in particular, the connection of one tubular to another becomesdifficult. Connectors or connection systems designed for conventionaltubulars do not readily adapt to tubular members that are expanded.

The present invention is directed to overcoming, or at least reducingthe effects of one or more of the problems set forth above, and can beuseful in other applications as well.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a technique isprovided for connecting tubulars, such as those used within a wellbore.The technique is particularly amenable to use with expandable tubulars.The technique allows such expandable tubulars to be connected and yetexpanded as desired. Certain connectors utilized with this technique areparticularly helpful in connecting tubulars formed of bistable cellsthat facilitate expansion of the tubular from a contracted stable stateto an expanded stable state.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

FIGS. 1A and 1B are illustrations of the forces imposed to make abistable structure;

FIG. 2A and 2B show force-deflection curves of two bistable structures;

FIGS. 3A–3F illustrate expanded and collapsed states of three bistablecells with various thickness ratios;

FIGS. 4A and 4B illustrate a bistable expandable tubular in its expandedand collapsed states;

FIGS. 4C and 4D illustrate a bistable expandable tubular in collapsedand expanded states within a wellbore;

FIGS. 5A and 5B illustrate an expandable packer type of deploymentdevice;

FIGS. 6A and 6B illustrate a mechanical packer type of deploymentdevice;

FIGS. 7A–7D illustrate an expandable swage type of deployment device;

FIGS. 8A–8D illustrate a piston type of deployment device;

FIGS. 9A and 9B illustrate a plug type of deployment device;

FIGS. 10A and 10B illustrate a ball type of deployment device;

FIG. 11 is a schematic of a wellbore utilizing an expandable bistabletubular;

FIG. 12 illustrates a motor driven radial roller deployment device;

FIG. 13 illustrates a hydraulically driven radial roller deploymentdevice;

FIG. 14 is a partial side elevational view of an alternative embodimentof the present invention;

FIG. 15 is a partial side elevational view of an alternative embodimentof the present invention;

FIGS. 16A–E are partial elevational views of an alternative embodimentof the present invention;

FIGS. 17A–D are partial perspective views of an alternative embodimentof the present invention;

FIG. 18 is a side elevational view of an expandable slotted tubinghaving end extensions of the present invention;

FIG. 19 is a partial cross-sectional end view of an embodiment of theconnector of the present invention;

FIG. 20 is a partial cross-sectional side view of an embodiment of theconnector of the present invention;

FIGS. 21A–21E illustrate the sequential coupling of adjacent tubularswith a sand barrier;

FIG. 22 is a cross-sectional view taken generally along the axis of theconnected tubulars illustrated in FIG. 21C;

FIGS. 23A–23C illustrate an alternate embodiment of the connectionsystem illustrated in FIGS. 21A–21C;

FIGS. 24A–24C illustrate another alternate embodiment of the connectionsystem illustrated in FIGS. 21A–21C;

FIG. 25 is a side view of a crossover device according to one embodimentof the present invention;

FIG. 26 is a front view of an alternate embodiment of the crossoverdevice illustrated in FIG. 25; and

FIGS. 27A–27D illustrate another alternate embodiment of an exemplaryconnection system.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Bistable devices used in the present invention can take advantage of aprinciple illustrated in FIGS. 1A and 1B. FIG. 1A shows a rod 10 fixedat each end to rigid supports 12. If the rod 10 is subjected to an axialforce it begins to deform as shown in FIG. 1B. As the axial force isincreased rod 10 ultimately reaches its Euler buckling limit anddeflects to one of the two stable positions shown as 14 and 15. If thebuckled rod is now clamped in the buckled position, a force at rightangles to the long axis can cause the rod to move to either of thestable positions but to no other position. When the rod is subjected toa lateral force it must move through an angle β before deflecting to itsnew stable position.

Bistable systems are characterized by a force deflection curve such asthose shown in FIGS. 2A and 2B. The externally applied force 16 causesthe rod 10 of FIG. 1B to move in the direction X and reaches a maximum18 at the onset of shifting from one stable configuration to the other.Further deflection requires less force because the system now has anegative spring rate and when the force becomes zero the deflection tothe second stable position is spontaneous.

The force deflection curve for this example is symmetrical and isillustrated in FIG. 2A. By introducing either a precurvature to the rodor an asymmetric cross section the force deflection curve can be madeasymmetric as shown in FIG. 2B. In this system the force 19 required tocause the rod to assume one stable position is greater than the force 20required to cause the reverse deflection. The force 20 must be greaterthan zero for the system to have bistable characteristics.

Bistable structures, sometimes referred to as toggle devices, have beenused in industry for such devices as flexible discs, over center clamps,hold-down devices and quick release systems for tension cables (such asin sailboat rigging backstays).

Instead of using the rigid supports as shown in FIGS. 1A and 1B, a cellcan be constructed where the restraint is provided by curved strutsconnected at each end as shown in FIGS. 3A–3F. If both struts 21 and 22have the same thickness as shown in FIGS. 3A and 3B, the forcedeflection curve is linear and the cell lengthens when compressed fromits open position FIG. 3B to its closed position FIG. 3A. If the cellstruts have different thicknesses, as shown in FIGS. 3C–3F, the cell hasthe force deflection characteristics shown in FIG. 2B, and does notchange in length when it moves between its two stable positions. Anexpandable bistable tubular can thus be designed so that as the radialdimension expands, the axial length remains constant. Intone example, ifthe thickness ratio is over approximately 2:1, the heavier strut resistslongitudinal changes. By changing the ratio of thick-to-thin strutdimensions, the opening and closing forces can be changed. For example,FIGS. 3C and 3D illustrated a thickness ratio of approximately 3:1, andFIGS. 3E and 3F illustrate a thickness ratio of approximately 6:1.

An expandable bore bistable tubular, such as casing, a tube, a patch, orpipe, can be constructed with a series of circumferential bistableconnected cells 23 as shown in FIGS. 4A and 4B, where each thin strut 21is connected to a thick strut 22. The longitudinal flexibility of such atubular can be modified by changing the length of the cells and byconnecting each row of cells with a compliant link. Further, the forcedeflection characteristics and the longitudinal flexibility can also bealtered by the design of the cell shape. FIG. 4A illustrates anexpandable bistable tubular 24 in its expanded configuration while FIG.4B illustrates the expandable bistable tubular 24 in its contracted orcollapsed configuration. Within this application the term “collapsed” isused to identify the configuration of the bistable element or device inthe stable state with the smallest diameter, it is not meant to implythat the element or device is damaged in any way. In the collapsedstate, bistable tubular 24 is readily introduced into a wellbore 29, asillustrated in FIG. 4C. Upon placement of the bistable tubular 24 at adesired wellbore location, it is expanded, as illustrated in FIG. 4D.

The geometry of the bistable cells is such that the tubularcross-section can be expanded in the radial direction to increase theoverall diameter of the tubular. As the tubular expands radially, thebistable cells deform elastically until a specific geometry is reached.At this point the bistable cells move, e.g. snap, to a final expandedgeometry. With some materials and/or bistable cell designs, enoughenergy can be released in the elastic deformation of the cell (as eachbistable cell snaps past the specific geometry) that the expanding cellsare able to initiate the expansion of adjoining bistable cells past thecritical bistable cell geometry. Depending on the deflection curves, aportion or even an entire length of bistable expandable tubular can beexpanded from a single point.

In like manner if radial compressive forces are exerted on an expandedbistable tubular, it contracts radially and the bistable cells deformelastically until a critical geometry is reached. At this point thebistable cells snap to a final collapsed structure. In this way theexpansion of the bistable tubular is reversible and repeatable.Therefore the bistable tubular can be a reusable tool that isselectively changed between the expanded state as shown in FIG. 4A andthe collapsed state as shown in FIG. 4B.

In the collapsed state, as in FIG. 4B, the bistable expandable tubularis easily inserted into the wellbore and placed into position. Adeployment device is then used to change the configuration from thecollapsed state to the expanded state.

In the expanded state, as in FIG. 4A, design control of the elasticmaterial properties of each bistable cell can be such that a constantradial force can be applied by the tubular wall to the constrainingwellbore surface. The material properties and the geometric shape of thebistable cells can be designed to give certain desired results.

One example of designing for certain desired results is an expandablebistable tubular string with more than one diameter throughout thelength of the string. This can be useful in boreholes with varyingdiameters, whether designed that way or as a result of unplannedoccurrences such as formation washouts or keyseats within the borehole.This also can be beneficial when it is desired to have a portion of thebistable expandable device located inside a cased section of the wellwhile another portion is located in an uncased section of the well. FIG.11 illustrates one example of this condition. A wellbore 40 is drilledfrom the surface 42 and comprises a cased section 44 and an openholesection 46. An expandable bistable device 48 having segments 50, 52 withvarious diameters is placed in the well. The segment with a largerdiameter 50 is used to stabilize the openhole section 46 of the well,while the segment having a reduced diameter 52 is located inside thecased section 44 of the well.

Bistable collars or connectors 24A (see FIG. 4C) can be designed toallow sections of the bistable expandable tubular to be joined togetherinto a string of useful lengths using the same principle as illustratedin FIG. 4A and 4B. This bistable connector 24A also incorporates abistable cell design that allows it to expand radially using the samemechanism as for the bistable expandable tubular component. Exemplarybistable connectors have a diameter slightly larger than the expandabletubular sections that are being joined. The bistable connector is thenplaced over the ends of the two sections and mechanically attached tothe expandable tubular sections. Mechanical fasteners such as screws,rivets or bands can be used to connect the connector to the tubularsections. The bistable connector typically is designed to have anexpansion rate that is compatible with the expandable tubular sections,so that it continues to connect the two sections after the expansion ofthe two segments and the connector.

Alternatively, the bistable connector can have a diameter smaller thanthe two expandable tubular sections joined. Then, the connector isinserted inside of the ends of the tubulars and mechanically fastened asdiscussed above. Another embodiment would involve the machining of theends of the tubular sections on either their inner or outer surfaces toform an annular recess in which the connector is located. A connectordesigned to fit into the recess is placed in the recess. The connectorwould then be mechanically attached to the ends as described above. Inthis way the connector forms a relatively flush-type connection with thetubular sections.

A conveyance device 31 transports the bistable expandable tubularlengths and bistable connectors into the wellbore and to the correctposition. (See FIGS. 4C and 4D). The conveyance device may utilize oneor more mechanisms such as wireline cable, coiled tubing, coiled tubingwith wireline conductor, drill pipe, tubing or casing.

A deployment device 33 can be incorporated into the overall assembly toexpand the bistable expandable tubular and connectors. (See FIGS. 4C and4D). Deployment devices can be of numerous types such as an inflatablepacker element, a mechanical packer element, an expandable swage, apiston apparatus, a mechanical actuator, an electrical solenoid, a plugtype apparatus, e.g. a conically shaped device pulled or pushed throughthe tubing, a ball type apparatus or a rotary type expander as furtherdiscussed below.

An inflatable packer element is shown in FIGS. 5A and 5B and is a devicewith an inflatable bladder, element, or bellows incorporated into thebistable expandable tubular system bottom hole assembly. In theillustration of FIG. 5A, the inflatable packer element 25 is locatedinside the entire length, or a portion, of the initial collapsed statebistable tubular 24 and any bistable expandable connectors (not shown).Once the bistable expandable tubular system is at the correct deploymentdepth, the inflatable packer element 25 is expanded radially by pumpingfluid into the device as shown in FIG. 5B. The inflation fluid can bepumped from the surface through tubing or drill pipe, a mechanical pump,or via a downhole electrical pump which is powered via wireline cable.As the inflatable packer element 25 expands, it forces the bistableexpandable tubular 24 to also expand radially. At a certain expansiondiameter, the inflatable packer element causes the bistable cells in thetubular to reach a critical geometry where the bistable “snap” effect isinitiated, and the bistable expandable tubular system expands to itsfinal diameter. Finally the inflatable packer element 25 is deflated andremoved from the deployed bistable expandable tubular 24.

A mechanical packer element is shown in FIGS. 6A and 6B and is a devicewith a deformable plastic element 26 that expands radially whencompressed in the axial direction. The force to compress the element canbe provided through a compression mechanism 27, such as a screwmechanism, cam, or a hydraulic piston. The mechanical packer elementdeploys the bistable expandable tubulars and connectors in the same wayas the inflatable packer element. The deformable plastic element 26applies an outward radial force to the inner circumference of thebistable expandable tubulars and connectors, allowing them in turn toexpand from a contracted position (see FIG. 6A) to a final deploymentdiameter (see FIG. 6B).

An expandable swage is shown in FIGS. 7A–7D and comprises a series offingers 28 that are arranged radially around a conical mandrel 30. FIGS.7A and 7C show side and top views respectively. When the mandrel 30 ispushed or pulled through the fingers 28 they expand radially outwards,as illustrated in FIGS. 7B and 7D. An expandable swage is used in thesame manner as a mechanical packer element to deploy a bistableexpandable tubular and connector.

A piston type apparatus is shown in FIGS. 8A–8D and comprises a seriesof pistons 32 facing radially outwardly and used as a mechanism toexpand the bistable expandable tubulars and connectors. When energized,the pistons 32 apply a radially directed force to deploy the bis tableexpandable tubular assembly as per the inflatable packer element. FIGS.8A and 8C illustrate the pistons retracted while FIGS. 8B and 8D showthe pistons extended. The piston type apparatus can be actuatedhydraulically, mechanically or electrically.

A plug type actuator is illustrated in FIGS. 9A and 9B and comprises aplug 34 that is pushed or pulled through the bistable expandabletubulars 24 or connectors as shown in FIG. 9A. The plug is sized toexpand the bistable cells past their critical point where they will snapto a final expanded diameter as shown in FIG. 9B.

A ball type actuator is shown in FIGS. 10A and 10B and operates when anoversized ball 36 is pumped through the middle of the bistableexpandable tubulars 24 and connectors. To prevent fluid losses throughthe cell slots, an expandable elastomer based liner 38 is run inside thebistable expandable tubular system. The liner 38 acts as a seal andallows the ball 36 to be hydraulically pumped through the bistabletubular 24 and connectors. The effect of pumping the ball 36 through thebistable expandable tubulars 24 and connectors is to expand the cellgeometry beyond the critical bistable point, allowing full expansion totake place as shown in FIG. 10B. Once the bistable expandable tubularsand connectors are expanded, the elastomer sleeve 38 and ball 36 arewithdrawn.

Radial roller type actuators also can be used to expand the bistabletubular sections. FIG. 12 illustrates a motor driven expandable radialroller tool. The tool comprises one or more sets of arms 58 that areexpanded to a set diameter by means of a mechanism and pivot. On the endof each set of arms is a roller 60. Centralizers 62 can be attached tothe tool to locate it correctly inside the wellbore and the bistabletubular 24. A motor 64 provides the force to rotate the whole assembly,thus turning the roller(s) circumferentially inside the wellbore. Theaxis of the roller(s) is such as to allow the roller(s) to rotate freelywhen brought into contact with the inner surface of the tubular. Eachroller can be conically-shaped in section to increase the contact areaof roller surface to the inner wall of the tubular. The rollers areinitially retracted and the tool is run inside the collapsed bistabletubular. The tool is then rotated by the motor 64, and rollers 60 aremoved outwardly to contact the inner surface of the bistable tubular.Once in contact with the tubular, the rollers are pivoted outwardly agreater distance to apply an outwardly radial force to the bistabletubular. The outward movement of the rollers can be accomplished viacentrifugal force or an appropriate actuator mechanism coupled betweenthe motor 64 and the rollers 60.

The final pivot position is adjusted to a point where the bistabletubular can be expanded to the final diameter. The tool is thenlongitudinally moved through the collapsed bistable tubular, while themotor continues to rotate the pivot arms and rollers. The rollers followa shallow helical path 66 inside the bistable tubular, expanding thebistable cells in their path. Once the bistable tubular is deployed, thetool rotation is stopped and the roller retracted. The tool is thenwithdrawn from the bistable tubular by a conveyance device 68 that alsocan be used to insert the tool.

FIG. 13 illustrates a hydraulically driven radial roller deploymentdevice. The tool comprises one or more rollers 60 that are brought intocontact with the inner surface of the bistable tubular by means of ahydraulic piston 70. The outward radial force applied by the rollers canbe increased to a point where the bistable tubular expands to its finaldiameter. Centralizers 62 can be attached to the tool to locate itcorrectly inside the wellbore and bistable tubular 24. The rollers 60are initially retracted and the tool is run into the collapsed bistabletubular 24. The rollers 60 are then deployed and push against the insidewall of the bistable tubular 24 to expand a portion of the tubular toits final diameter. The entire tool is then pushed or pulledlongitudinally through the bistable tubular 24 expanding the entirelength of bistable cells 23. Once the bistable tubular 24 is deployed inits expanded state, the rollers 60 are retracted and the tool iswithdrawn from the wellbore by the conveyance device 68 used to insertit. By altering the axis of the rollers 60, the tool can be rotated viaa motor as it travels longitudinally through the bistable tubular 24.

Power to operate the deployment device can be drawn from one or acombination of sources such as: electrical power supplied either fromthe surface or stored in a battery arrangement along with the deploymentdevice, hydraulic power provided by surface or downhole pumps, turbinesor a fluid accumulator, and mechanical power supplied through anappropriate linkage actuated by movement applied at the surface orstored downhole such as in a spring mechanism.

The bistable expandable tubular system is designed so the internaldiameter of the deployed tubular is expanded to maintain a maximumcross-sectional area along the expandable tubular. This feature enablesmono-bore wells to be constructed and facilitates elimination ofproblems associated with traditional wellbore casing systems where thecasing outside diameter must be stepped down many times, restrictingaccess, in long wellbores.

The bistable expandable tubular system can be applied in numerousapplications such as an expandable open hole liner where the bistableexpandable tubular 24 is used to support an open hole formation byexerting an external radial force on the wellbore surface. As bistabletubular 24 is radially expanded, the tubular moves into contact with thesurface forming wellbore 29. These radial forces help stabilize theformations and allow the drilling of wells with fewer conventionalcasing strings. The open hole liner also can comprise a material, e.g. awrapping, that reduces the rate of fluid loss from the wellbore into theformations. The wrapping can be made from a variety of materialsincluding expandable metallic and/or elastomeric materials. By reducingfluid loss into the formations, the expense of drilling fluids can bereduced and the risk of losing circulation and/or borehole collapse canbe minimized.

Liners also can be used within wellbore tubulars for purposes such ascorrosion protection. One example of a corrosive environment is theenvironment that results when carbon dioxide is used to enhance oilrecovery from a producing formation. Carbon dioxide (CO₂) readily reactswith any water (H₂O) that is present to form carbonic acid (H₂CO₃).Other acids can also be generated, especially if sulfur compounds arepresent. Tubulars used to inject the carbon dioxide,as well as thoseused in producing wells are subject to greatly elevated corrosion rates.The present invention can be used to, place protective liners, e.g. abistable tubular 24, within an existing tubular to minimize thecorrosive effects and to extend the useful life of the wellboretubulars.

Another exemplary application involves use of the bistable tubular 24 asan expandable perforated liner. The open bistable cells in the bistableexpandable tubular allow unrestricted flow from the formation whileproviding a structure to stabilize the borehole.

Still another application of the bistable tubular 24 is as an expandablesand screen where the bistable cells are sized to act as a sand controlscreen. Also, a filter material can be combined with the bistabletubular as explained below. For example, an expandable screen elementcan be affixed to the bistable expandable tubular. The expandable screenelement can be formed as a wrapping around bistable tubular 24. It hasbeen found that the imposition of hoop stress forces onto the wall of aborehole will in itself help stabilize the formation and reduce oreliminate the influx of sand from the producing zones, even if noadditional screen element is used.

The above described bistable expandable tubulars can be made in avariety of manners such as: cutting appropriately shaped paths throughthe wall of a tubular pipe thereby creating an expandable bistabledevice in its collapsed state; cutting patterns into a tubular pipethereby creating an expandable bistable device in its expanded state andthen compressing the device into its collapsed state; cuttingappropriate paths through a sheet of material, rolling the material intoa tubular shape and joining the ends to form an expandable bistabledevice in its collapsed state; or cutting patterns into a sheet ofmaterial, rolling the material into a tubular shape, joining theadjoining ends to form an expandable bistable device in its expandedstate and then compressing the device into its collapsed state.

The materials of construction for the bistable expandable tubulars caninclude those typically used within the oil and gas industry such ascarbon steel. They can also be made of specialty alloys (such as amonel, inconel, hastelloy or tungsten-based alloys) if the applicationrequires.

The configurations shown for the bistable tubular 24 are illustrative ofthe operation of a basic bistable cell. Other configurations may besuitable, but the concept presented is also valid for these othergeometries.

Referring generally to FIGS. 14 and 15, a side elevational view and aperspective view, respectively, are used to illustrated an expandabletubing 80 made of bi-stable cells 81. As previously described, thebi-stable cells 81 are generally formed of a thin strut 21 and a thickstrut 22 which intersect at either end 84. In the exemplary embodimentshown in the figures, the end 82 of the tubing 80 comprises a pluralityof end extensions 86. The end extensions 86 are connected to an end 84of the cells 81 nearest the tubing end 82 so that the end extensions 86extend beyond the cells 81 of the tubing. The tubing may have endextensions on one or both ends thereof.

Further, although the figure illustrates an end extension on all of theendmost cells, alternative embodiments may have end extensions 86 onsome portion of such cells only. The end extensions 86 are useful forconnecting adjacent expandable tubings as further discussed below aswell as for other uses. Note that the end extensions do not undergodeformation as the tubing is expanded. The end extensions may beintegrally formed or otherwise attached such as by welding or otherattachment methods.

Referring generally to FIGS. 16A–E, a detailed sequence is illustratedof one embodiment of end extensions 86 being connected to adjacenttubings having an associated connector 90. As shown in the figures, oneof the end extensions 86 includes an opening 92 formed therein. Althoughshown as a slot in the FIGS. 16A–E, the opening 92 may take other formssuch as a hole drilled in the end, collets, or other types of openings92. The opening 92 of the disclosed embodiment forms a narrow outerportion 94 and a wide inner portion 96. The opening 92 also may have aslot 98 at the back of the opening 92. The end 100 of the end extension86 has a slanted, or tapered, interior 102 and a slanted, or tapered,exterior 104. Although shown as slanted, the end 100 may be blunt,rounded or some other shape.

A pin 110 mounted to the end of a corresponding extension 86 has a broadhead 112 with a slanted forward face 114. The pin 110 is shaped andsized to mate with the opening 92. The figures show how the pin 110passes through the outer portion 94 of the opening 92. As the pin 110passes through the outer portion 94, the opposing sides flex outwardly(FIG. 16B) to accommodate the relatively larger head 112. Once the headis positioned in the inner portion 96 (FIG. 16C), the sides may flexback to their original position or near their original position. Theslot 98 may provide added resiliency to facilitate placement of the pin110 in the opening 92.

Once the head 112 is positioned inside the opening 92, sleeve 120 slidesover the mating pin 110 and opening 92 to maintain them in matingconnection (see FIGS. 16D and 16E). The slanted exterior 104 of the endextension 86 facilitates movement of the sleeve 120 thereon. Note thatthe sleeve may be replaced by a clip surrounding the mating pin 110 andopening 92 or other device that can maintain the relative position ofthe mating pieces.

It should also be noted that in one embodiment, the head 112 providesfor some plastic deformation of the sides of the end extension 86 sothat the sides remain slightly flared. The flared sides provide forincreased friction useful in holding the sleeve in place. Alternativelythe end extensions 86 may provide detents or other mechanisms to preventthe sleeve from slipping out of position.

Referring to FIGS. 17A–D, an alternative embodiment for connecting theend extensions 86 of adjacent tubings is illustrated. In thisembodiment, both end extensions 86 have openings 92 formed therein. Oncethe end extensions 86 are positioned adjacent one another, matingconnectors 122 are moved into the openings 92 to maintain the relativeposition of the end extensions 86. As with the prior embodiment, theconnector 122 has widened head portions 112 that fit within wide innerportions 96 of the openings 92. A sleeve 120 slides over the matingconnector 122 and openings 92 to help maintain their relative positions.Note that the connectors 122 may have detents or other features thateliminate the need for the sleeve 120. Alternatively, the sleeve 120 maybe replaced with a clip, adhesive, resin, tape, or other manner ofholding the connector 122 in the openings 92. Although the abovedescription relies on the use of end extensions 86 they may be omittedin certain alternative embodiments with the openings formed at the endof the endmost cells.

Also, note that other types of expandable tubings may benefit from theconnection type taught herein. For example, as illustrated in FIG. 18,an expandable slotted tube 130 of the type disclosed in U.S. Pat. No.5,366,012, issued Nov. 22, 1994 to Lohbeck has overlapping longitudinalslots. As can be viewed in FIG. 18, tubing 130 has end extensions 86with openings 92 formed therein. The end extensions and openings may beused to connect the tubing 130 to an adjacent tubing in a manner similarto that previously described. As with the other embodiments, these typesof connectors readily allow expansion of the connected ends of thetubulars along with the rest of the tubular as opposed to thetraditional connection systems that are not as amenable to expansion.

In FIG. 19, another alternative embodiment is illustrated in which theconnector 122 has sides 142 that slant inwardly approaching one end. Thesides 140 of the mating opening 92 also slant inwardly such that theconnector 122 may be placed in the opening in one direction only. Thetolerance between the opening 92 and the connector 122 holds theconnector in place in one direction. The slanted surfaces 140, 142 maybe replaced with equivalents such as shoulders and the like. Theembodiment shown also has a clip 144 with resilient side arms anddetents 146 that mate with indentations 148 formed in the end extensions86. The detents 146 and indentations 148 mate to hold the clip 144 onthe end extension 86. The clip 144 is placed on the side through whichthe connector 122 is placed.

Illustrated in FIG. 20 is another alternative embodiment in which theopenings 92 do not open to the ends of the end extensions 86. Aconnector 150 has side members 152 that are coupled to retention members154. Retention members 154 are sized to extend through the openings 92into engagement with side members 152. Side members 152 may be coupledto retention members by a variety of mechanisms including snap fits,permanent fixation or fasteners. The tensile strength of the combinedconnections should be sufficient to prevent separation of the connectedtubings. Accordingly, the connector may be formed of a material that isdifferent from the material of the tubing.

Referring generally to FIGS. 21A–21C, another embodiment of anexpandable connection system is illustrated. In this embodiment, a firsttubular 160 is coupled to a second tubular 162 by a connection system164. First tubular 160 and second tubular 162 may be comprised of aplurality of bistable cells, as described above. Additionally,connection system 164 may be designed to function similarly to theembodiments described above.

As illustrated, connection system 164 comprises a receiving end 166extending from first tubular 160 and an insertion end 168 extending fromsecond tubular 162. The exemplary receiving end 166 comprises aplurality of extensions 170 that define a plurality of openings 172 eachhaving a narrow outer portion 174 and a wider inner portion 176 similarto openings described above. Insertion end 168 comprises a plurality ofpins or broad heads 178 that may be tapered towards a leading edge forinsertion into openings 172 through the narrow outer portions 174. Eachof the pins 178 includes a recessed retention feature 179 designed toengage a corresponding retention feature 180 of each extension 170.Retention features 179 and 180 are designed to prevent inadvertentseparation of first tubular 160 and second tubular 162. Additionally, aretention member 181, e.g. an expandable slide cover, is mounted to atleast one of first tubular 160 and second tubular 162. In the embodimentillustrated, retention member 181 is slidably mounted to first tubular160 such that it may be moved over extensions 170 and pins 178 aftercoupling of first tubular 160 to second tubular 162 to secure theconnection. In the example illustrated, retention features 179 and 180do not extend radially outward beyond the outside diameter of firsttubular 160 and second tubular 162. Thus, the outside diameter of thecollective extensions of connector system 164 does not exceed theoutside diameters of first and second tubulars 160 and 162.

An exemplary retention member 181 is a slide cover comprising aplurality of separable sections 182 that each have a pair oflongitudinal openings 183 through which a pair of cooperating extensions170 are received (see FIGS. 21D and 21E). When the slide cover is in adisengaged position as illustrated in FIG. 21A, cooperating extensions170 may be sufficiently spread to receive a pin 178 as illustrated inFIG. 21B. Once extensions 170 and pins 178 are interlocked, 5 the slidecover is moved to an engaged position, as illustrated in FIG. 21C. Inthis engaged position, extensions 170 are prevented from spreading byvirtue of their capture within openings 183. Separable sections 182 maybe independent of each other or connected by an expandable material orflexible connection that permits radial expansion of retention member181.

Additionally, the slide cover may comprise one or more integratedlocking devices 184 used to hold the slide cover in its-engagedposition, although the locking devices also can be used to hold theslide cover in the disengaged position. An exemplary locking device 184comprises a plurality of threaded studs 185 threadably received throughcorresponding sections 182. One or more of the threaded studs 185 may berotated and moved radially inwardly to hold the slide cover or at leastthe corresponding section 182 at a desired location. For example, whenthe slide cover is moved to the engaged position, threaded studs 185 arerotated inwardly, as illustrated in FIGS. 21E and 22, to prevent theslide cover from being inadvertently moved to the disengaged position.Specifically, extensions 170 are designed to block movement of the studs185 towards a disengaged position once threaded radially inwardly asufficient amount.

Additionally, connection system 164 may comprise a sand barrier 186designed to limit the influx of sand through connection system 164. Inthis embodiment, sand barrier 186 is disposed along the interior ofconnection system 164. For example, at least a portion of sand barrier186 may be coupled to the interior of first tubular 160 such that itextends beyond extensions 170. (See FIG. 21A). When first tubular 160and second tubular 162 are moved together, sand barrier 186 moves intothe interior of second tubular 162 as pins 178 are inserted intoopenings 172, as illustrated best in FIG. 21B. Following insertion,slide cover 181 is moved towards second tubular 162 and over theinterlocked extensions 170 and 178 to further assist in preventingunwanted separation of the tubular components.

Referring generally to FIG. 22, one exemplary embodiment of thisinternal type of sand barrier is illustrated. In this embodiment, a sandbarrier sand sleeve 188 is connected to the interior of first tubular160 by, for example, a plurality of pins 190 received in correspondingslots 192 formed in tubular 160. Another exemplary mechanism forfastening sand barrier sleeve 188 to tubular 160 is a plurality ofweldments placed on selected portions of the tubular so as to notinterfere with expansion. Weldments can be used alone or in addition toother retention features, such as pins 190. A barrier cap 194 is affixedto second tubular 162 by, for example, pins 196 and/or appropriateweldments. Barrier cap 194 comprises a recessed region 198 for receivingand holding sand barrier sleeve 188 when first tubular 160 and secondtubular 162 are coupled together. A plurality of barrier sheets 199 maybe combined with or incorporated into sand sleeve 188. Exemplary barriersheets 199 comprise overlapping, metallic sheets that permit expansionof the sand barrier 186 without effecting blockage of sand influx. Otherexemplary barriers comprise woven filtration materials, slotted metallicsheets with slots sized according to desired filtration parameters, orelastomeric materials.

An alternate embodiment of the sand barrier is illustrated in FIGS.23A–23C and labeled as sand barrier 200. In this embodiment, theillustrated connection system 164 is similar to that shown and describedin FIGS. 21A–21C. Sand barrier 200, however, is an external sand barriersimilar in design to the interior sand barrier 186, except disposed toslide over the exterior of connection system 164.

For example, sand barrier 200 may be attached along the exterior offirst tubular 160 by appropriate fasteners, weldments, etc., asillustrated best in FIGS. 23A and 23C. As insertion end 168 of secondtubular 162 is moved into engagement with receiving end 166 of firsttubular 160, sand barrier 200 moves over second tubular 162 and coversconnection system 164, as best illustrated in FIG. 23B. One exemplarysand barrier 200 comprises an outer shroud 202 covering one or morebarrier sheets 204 (see FIG. 23C), however a variety of layers andmaterials can be combined to create the sand barrier. An exemplary sandbarrier is made from a material that is hyperelastic, capable of shapememory, or made from other expandable materials, such as titaniumalloys, to achieve the desired expansion effect.

Another exemplary embodiment of a sand barrier is illustrated in FIGS.24A–24C. In this embodiment, a sand barrier 210 comprises an expandableshroud and filter layer 212 that is pulled over a first run-in guide214, as illustrated in FIG. 24A. The shroud and filter layer 212 ismoved over run-in guide 214 (see FIG. 24B) until it is positionedgenerally between run-in guide 214 and a secondary run-in guide 216, asillustrated best in FIG. 24C.

Referring generally to FIGS. 25 and 26, additional embodiments of thepresent invention are illustrated in the form of crossover devices. Forexample, in FIG. 25, an expandable crossover 220 is illustrated.Expandable crossover 220 comprises an expandable section 222 and a solidsection 224. Crossover 220 typically comprises a connector end 226having, for example, internal threads for threaded engagement with anadjacent component. Also, the expandable section may be formed with oneor more bistable cells.

Additionally, expandable crossover 220 comprises a connector 228generally opposite connector end 226. Connector 228 may be any of avariety of the connectors described above including, for example, aplurality of extension pins designed for receipt in correspondingextensions. Furthermore, any of the variety of sand barriers discussedabove can be combined with expandable crossover 220 proximate connector228.

Expandable section 222 also may comprise or be combined with a varietyof other components. For example, sand filtration materials and outershrouds may be incorporated into the design of expandable section 222.Furthermore, expandable section 222 may be surrounded with anelastomeric material, e.g. rubber jacket, for a variety of applications.These are just a few examples illustrating the adaptability of thecrossover device.

In another embodiment illustrated in FIG. 26, the crossover is a rigidcrossover 230. Though the rigid crossover 230 is not expanded, it can becombined with an expandable-style connector 232. With connector 232,expandable sand barriers, such as those discussed above, can beincorporated into the design to limit the influx of sand throughconnector 232. Opposite connector 232, rigid crossover 230 comprises aconnector end 234 that may be tapered and comprise a threaded region236.

Referring generally to FIGS. 27A–27D, another technique is illustratedfor coupling the first tubular 160 with the second tubular 162. Thetechnique may be utilized with expandable and non-expandable tubulars.

In this embodiment, a connector system 240 is used to couple firsttubular 160 with second tubular 162. Connector system 240 comprises afirst connector portion 242 coupled to first tubular 160 and a secondconnector portion 244 coupled to second tubular 162. First and secondconnector portions 242, 244 may be separate components attached to thecorresponding tubulars, or they may be integrally formed with thetubulars.

First connector portion 242 comprises a plurality of extensions 246separated by gaps 248, as illustrated best in FIG. 27A. Similarly,second connector portion 244 comprises a plurality of axial extensions250 separated by axial gaps 252. Axial gaps 252 are sized to receiveextensions 246, and gaps 248 are sized to receive axial extensions 250,as illustrated in FIG.27B.

Furthermore, extensions 246 comprise a first interlock mechanism 254,and axial extensions 250 comprise a second interlock mechanism 256designed to engage first interlock mechanism 254. Connector system 240becomes interlocked when extensions 246, 250 are moved axially intotheir cooperating gaps 252, 248, respectively, and tubulars 160 and 162are rotated with respect to each other, as illustrated best in FIG. 27C.In the specific embodiment illustrated, first interlock mechanism 254comprises a plurality of circumferentially oriented ridges 258 separatedby spaces 260. The circumferentially oriented ridges 258 extend radiallyinwardly.

Similarly, an exemplary second interlock mechanism 256 comprises aplurality of outwardly extending ridges 262 separated by spaces 264.Outwardly extending ridges 262 are circumferentially oriented forreceipt in spaces 260 when first tubular 160 and second tubular 162 arerotated to interlock connector system 240. Similarly, ridges 258 aresized and oriented for receipt in spaces 264 when connector system 240is interlocked.

To secure the interlocking of extensions 246 with axial extensions 250,one or more sleeves, such as sliding covers 266, may be mounted overselected extensions, as illustrated in FIGS. 27C and 27D. For example,sliding cover or covers 266 may be slidably disposed on one of the axialextensions 250. The sliding cover is positioned at a location that doesnot interfere with the insertion of extensions 246 into axial gaps 252or the rotation of first interlock mechanism 254 into engagement withsecond interlock mechanism 256, as illustrated best in FIG. 27C.

Once interlocked, each of the one or more sliding covers 266 is slidover the mating first interlock mechanism 254 and second interlockmechanism 256, as illustrated best in FIG. 27D. The sliding cover 266 issized to prevent the interlocked ridges 258 and 262 from separatingand/or rotating with respect to each other. If desired, each slidingcover 266 may be held at a desired location over first interlockmechanism 254 and second interlock mechanism 256 by, for example, afriction fit, detents, set screws, a weldment or other fasteningmechanisms.

In some applications, first tubular 160 and/or second tubular 162 areexpanded within the wellbore. The unique design of interlockedextensions with gaps therebetween allows connector system 240 to beexpanded along with tubulars 160 and 162.

The particular embodiments disclosed herein are illustrative only, asthe invention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Furthermore, no limitations are intended to thedetails of construction or design herein shown, other than as describedin the claims below. It is therefore evident that the particularembodiments disclosed above may be altered or modified and all suchvariations are considered within the scope and spirit of the invention.Accordingly, the protection sought herein is as set forth in the claimsbelow.

1. A system of expandable tubulars, comprising: a first radiallyexpandable tubular; a second radially expandable tubular; and aconnector system coupling the first tubular to the second tubular, theconnector system having a plurality of interlocking extensionscomprising receiving extensions extending from the first tubular andinsertion extensions extending from the second tubular, each insertionextension having an expanded region and each receiving extension havinga connector opening with a narrow outer portion and a wider innerportion to receive a corresponding expanded region, the correspondinginsertion extension being configured to be axially inserted into thereceiving extension and spreading the narrow outer portion until theexpanded region is captured in the wider inner portion to automaticallyinterlock the insertion extension and the receiving extension.
 2. Thesystem as recited in claim 1, further comprising a slide coverpositioned to secure the plurality of interlocking extensions.
 3. Thesystem as recited in claim 1, wherein the receiving extensions extendfrom an end of the first tubular and the insertion extensions extendfrom an adjacent end of the second tubular.
 4. The system as recited inclaim 1, wherein the connector system comprises a sand barrier.
 5. Thesystem as recited in claim 4, wherein the sand barrier is positionedalong the interior of the first tubular and the second tubular.
 6. Thesystem as recited in claim 4, wherein the sand barrier is positionedalong the exterior of the first tubular and the second tubular.
 7. Aconnector system for connecting a pair of adjacent radially expandabletubulars, comprising, a plurality of connector portions extending from afirst radially expandable tubular, the plurality of connector portionsbeing separated by connector portion gaps formed through a wall of thefirst tubular; a plurality of corresponding connector portions disposedat an end of a second radially expandable tubular, the plurality ofcorresponding connector portions being separated by correspondingconnector portion gaps formed through a wall of the second radiallyexpandable tubular, the plurality of connector portions being configuredto interlockingly receive the corresponding connector portions when thefirst radially expandable tubular and the second radially expandabletubular are rotated with respect to each other; and a sand barrierpositioned along the plurality of connector portions and the pluralityof corresponding connector portions when engaged.
 8. A connector systemfor connecting a pair of adjacent tubulars, comprising, a plurality ofconnector portions extending from a first tubular, the plurality ofconnector portions being separated by connector portion gaps formedthrough a wall of the first tubular; a plurality of correspondingconnector portions disposed at an end of a second tubular, the pluralityof corresponding connector portions being separated by correspondingconnector portion gaps formed through a wall of the second tubular, theplurality of connector portions being configured to interlockinglyreceive the corresponding connector portions when the first tubular andthe second tubular are rotated with respect to each other; and a sandbarrier positioned along the plurality of connector portions and theplurality of corresponding connector portions when engaged; wherein eachconnector portion comprises a plurality of spaced circumferentiallyoriented ridges extending radially inward, and each correspondingconnector portion comprises a plurality of corresponding ridgesextending radially outward for receipt between the spacedcircumferentially oriented ridges upon relative rotation of the firsttubular and the second tubular.
 9. The connector system as recited inclaim 8, further comprising a sleeve disposed around at least one of theconnector portions.
 10. The connector system as recited in claim 9,wherein the sleeve comprises a slide cover sized to slide over aninterlocked connector portion and corresponding connector portion.
 11. Asystem of tubulars, comprising: a first radially expandable tubular; asecond radially expandable tubular coupled to the first tubular via aconnector system; and a sand barrier disposed along the connectorsystem, the sand barrier being positioned to block influx ofparticulates into an interior of the first and second tubulars whenpositioned in a wellbore.
 12. The system as recited in claim 11, whereinthe sand barrier is external to the connector system.
 13. The system asrecited in claim 11, wherein the sand barrier is internal to theconnector system.
 14. A system of expandable tubulars, comprising: afirst radially expandable tubular; a second radially expandable tubular;and a slide cover slidably mounted on the first tubular, wherein theslide cover may be slid relative to the first tubular and intoengagement with the second tubular to secure the second tubular to thefirst tubular.
 15. The system as recited in claim 14, further comprisinga plurality of interlocking extensions disposed at adjacent ends of thefirst and second tubulars.
 16. The system as recited in claim 15,wherein the slide cover is disposed around the plurality of interlockingextensions to secure them in interlocked engagement.